[realtek] Use explicit values for RCR.RXFTH and RCR.MXDMA

Some RTL8169 cards (observed with an RTL8169SC) power up with invalid
values in RCR.RXFTH and RCR.MXDMA, causing receive DMA to fail.  Fix
by setting explicit values for both fields.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/realtek.c

 
 	/* Configure receiver */
 	rcr = readl ( rtl->regs + RTL_RCR );
-	rcr &= ~( RTL_RCR_RBLEN_MASK );
-	rcr |= ( RTL_RCR_RBLEN_DEFAULT | RTL_RCR_WRAP | RTL_RCR_AB |
+	rcr &= ~( RTL_RCR_RXFTH_MASK | RTL_RCR_RBLEN_MASK |
+		  RTL_RCR_MXDMA_MASK );
+	rcr |= ( RTL_RCR_RXFTH_DEFAULT | RTL_RCR_RBLEN_DEFAULT |
+		 RTL_RCR_MXDMA_DEFAULT | RTL_RCR_WRAP | RTL_RCR_AB |
 		 RTL_RCR_AM | RTL_RCR_APM | RTL_RCR_AAP );
 	writel ( rcr, rtl->regs + RTL_RCR );
 

src/drivers/net/realtek.h

 
 /** Receive (Rx) Configuration Register (dword) */
 #define RTL_RCR 0x44
+#define RTL_RCR_RXFTH(x)	( (x) << 13 ) /**< Receive FIFO threshold */
+#define RTL_RCR_RXFTH_MASK	RTL_RCR_RXFTH ( 0x7 )
+#define RTL_RCR_RXFTH_DEFAULT	RTL_RCR_RXFTH ( 0x7 /* Whole packet */ )
 #define RTL_RCR_RBLEN(x)	( (x) << 11 ) /**< Receive buffer length */
 #define RTL_RCR_RBLEN_MASK	RTL_RCR_RBLEN ( 0x3 )
 #define RTL_RCR_RBLEN_DEFAULT	RTL_RCR_RBLEN ( 0 /* 8kB */ )
+#define RTL_RCR_MXDMA(x)	( (x) << 8 ) /**< Max DMA burst size */
+#define RTL_RCR_MXDMA_MASK	RTL_RCR_MXDMA ( 0x7 )
+#define RTL_RCR_MXDMA_DEFAULT	RTL_RCR_MXDMA ( 0x7 /* Unlimited */ )
 #define RTL_RCR_WRAP		0x00000080UL /**< Overrun receive buffer */
 #define RTL_RCR_9356SEL		0x00000040UL /**< EEPROM is a 93C56 */
 #define RTL_RCR_AB		0x00000008UL /**< Accept broadcast packets */